1. Field of the Invention
The invention relates to trocars. More particularly, the invention relates to a trocar sealing structure.
2. Description of the Prior Art
A trocar assembly is a surgical instrument that is used to gain access to a body cavity. A trocar assembly generally comprises two major components, a trocar sleeve, composed of a trocar housing and a trocar cannula, and a trocar obturator. The trocar cannula, having the trocar obturator inserted therethrough, is directed through the skin to access a body cavity. Once the body cavity is accessed, laparoscopic or arthroscopic surgery and endoscopic procedures may be performed. In order to penetrate the skin, the distal end of the trocar cannula is placed against the skin that has been previously cut with a scalpel. The trocar obturator is then used to penetrate the skin and access the body cavity. By applying pressure against the proximal end of the trocar obturator, the sharp point of the trocar obturator is forced through the skin until it enters the body cavity. The trocar cannula is inserted through the perforation made by the trocar obturator and the trocar obturator is withdrawn, leaving the trocar cannula as an access way to the body cavity.
The proximal end portion of the trocar cannula is typically joined to a trocar housing that defines a chamber having an open distal end portion in communication with the interior lumen defined by the trocar cannula. A trocar obturator, or other elongated cylindrical surgical instruments or tools, axially extend into and are withdrawn from the trocar cannula through the proximal end portion of the chamber defined by the trocar housing.
Current trocar assemblies are commonly designed with a seal mechanism positioned within the chamber of the trocar housing. The sealing mechanisms are commonly a sealing grommet or gasket through which the trocar obturator or other instruments extend. The sealing mechanism seals against the outer surface of the inserted instruments and thereby prevents fluids and insufflation gas from leaving or entering the body cavity through the trocar cannula.
The sealing systems utilized in conjunction with trocar assemblies perform sealing in two configurations: 1) pneumostasis must be maintained when an instrument is present in the trocar and 2) pneumostasis must be maintained when no instrument is present in the trocar. Single seal systems are designed to maintain pneumostasis in both conditions through the utilization of a single seal structure. Multi-seal systems use two or more seals to achieve full system functionality. In multi-seal systems, the proximal seal is designed to engage instruments and maintain pneumostasis when an instrument is inserted through the trocar cannula while a separate distal seal is used to stop gas flow when the instrument is removed.
In use, it is desirable that seals offer good tear resistance, resistance to snagging and low friction with respect to the insertion or removal of surgical instruments. Angular insertions of instruments relative to the central axis of the trocar and instrument tip sharpness are driving factors in trocar seal failures. These two factors can cause “tenting” of the seal material. Once tenting occurs, continued distal motion of the penetrating instrument will result in seal tearing.
A need, therefore, exists for a trocar sealing assembly providing for good tear resistance, resistance to snagging and low friction with respect to the insertion or removal of surgical instruments. The present invention provides a reinforced seal assembly which overcomes the shortcomings of prior art seals.